By Raymond Cheung ‘22

Since trees can absorb greenhouse gases through photosynthesis, reforestation efforts are becoming a more crucial way to combat climate change. However, new research suggests that the number of tree species planted is as essential as the quantity. A recent study conducted by Yuanyuan Huang and more than sixty scientists from China, Switzerland, and Germany analyzed over 150,000 trees planted in the Jiangxi province (1). Their research spanned over eight years and examined sixteen tree species.

The researchers found that on average the most diverse forest absorbed 32 tons of carbon per hectare compared to the average 12 tons of carbon per hectare in the single-species forest. This may be due to the fact that varying species have different nutritional needs, so greater species diversity puts less pressure on a subset of nutrients within the soil, resulting in healthier soil overall. They were able to calculate carbon absorption by cutting down 100 trees and measuring their biomass volume and carbon intake. In addition to absorbing more carbon, species-rich forests were also less vulnerable to diseases, which was contributed to the biodiversity of the area.

Climate change poses a significant threat to ecosystems and humans. While it is important to explore other solutions to mitigate climate change, such as renewable energy, reforestation with multiple tree species is a more efficient and economical solution. According to the study, a 10% decrease in tree species diversity would lead to a 2.7% decrease in forest productivity, equivalent to a $20 billion loss of wood. In these reforestation efforts, the researchers also suggested planting native tree species, which can potentially yield even higher productivity and stability. By protecting natural rainforests and promoting reforestation with various tree species, the effects of climate change can be further mitigated.

References

1. Y. Huang, et. al., Impacts of species richness on productivity in a large-scale subtropical forest experiment. Science 362, 80-83 (2018). doi: https://doi.org/10.1126/science.aat6405  
2. Image retrieved from: https://www.pexels.com/photo/bright-countryside-dawn-daylight-302804/